well my 93 w250 will one day start right up and the next day ill have to crank on it for a while it start. I want to say that it seems to happen when the truck is parked on a slight hill."Hood higher then bed" when the truck starts is acts likes it was ran out of fuel misses a bit and then clears up i can shut off and it will start right back up. Im thinking maybe the lift pump valve leaks alowing fuel to drain back to tank any way to test? not sure if this is it because my 91s lift pump was shot and that run fine un till have changed the fuel filter. any input would help thanks

 

Sounds like you have air getting in the fuel line somewhere. I dont belive that there is a check valve or anything in the lp. The only thing that keeps the fuel from draining back is the fact that the fuel line is sealed and no air is supposed to get in.

 

I too would also check the fuel lines or just replace them. Also check the return lines back to the tank.